/Engine/Source/Editor/GraphEditor/Public/SNodePanel.h
Paint the background as lines.
void PaintBackgroundAsLines ( const [FSlateBrush](API\Runtime\SlateCore\Styling\FSlateBrush) * BackgroundImage, const [FGeometry](API\Runtime\SlateCore\Layout\FGeometry) & AllottedGeometry, const [FSlateRect](API\Runtime\SlateCore\Layout\FSlateRect) & MyCullingRect, [FSlateWindowElementList](API\Runtime\SlateCore\Rendering\FSlateWindowElementList) & OutDrawElements, int32 & DrawLayerId ) const